Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$118.89	5.447%	$125.3659	$125.37	$125.35	$125.40
Purchase #2	$145.79	13.467%	$165.4235	$165.42	$165.40	$165.40
Purchase #3	$127.77	4.743%	$133.8301	$133.83	$133.85	$133.80
Purchase #4	$80.85	10.815%	$89.5939	$89.59	$89.60	$89.60
Purchase #5	$47.55	10.277%	$52.4367	$52.44	$52.45	$52.40
Purchase #6	$247.41	11.304%	$275.3772	$275.38	$275.40	$275.40
Purchase #7	$194.30	11.163%	$215.9897	$215.99	$216.00	$216.00
7 purchase totals =	$962.56		$1,058.0170	$1,058.02	$1,058.05	$1,058.00